Thrust reversers are provided on jet engines typically to increase the amount of braking on an aircraft upon landing. When deployed, a thrust reverser will change the direction of thrust of the jet engine such that some or all of the thrust is directed forwards, which acts to slow the aircraft so that it can then taxi off the runway.
There are a number of types of thrust reverser, all of which must be stowed during normal aircraft operation, for example so that the thrust reverser cannot be deployed during take-off or at a cruise altitude and can only be deployed during landing. In order to ensure this, one or more lock members are provided to prevent unwanted deployment of the thrust reverser, and in particular the actuators that move the various parts of the thrust reverser assembly.
Most thrust reverser systems include primary, secondary and tertiary locks. Although this may depend on the particular configuration, the primary locks are typically coupled to the actuators of thrust reverser, the secondary locks may be coupled to the power drive unit of the actuators and the tertiary locks may be coupled directly to a thrust reverser component (e.g., a translating cowl).
Conventionally, solenoid valves have been used to provide electrically operated tertiary locks used in thrust reversers. These are typically only capable of operating short translations and low loads, since in order to provide longer translations and/or higher loads the size of the solenoid exceeds the usual specification requirements for aerospace applications. Due to the short translation of the solenoid in such applications, most conventional arrangements require the use of multiple springs, and a pivoting member between a hook style locking member and the solenoid.
It is desired to provide an electrically operated tertiary lock system that is lightweight, compact and avoids the need to use a hook style locking member.